mnemonicToEntropy function

String mnemonicToEntropy(dynamic mnemonic, String language)

Implementation

String mnemonicToEntropy(mnemonic, String language) {
  var words = mnemonic.split(' ');
  if (words.length % 3 != 0) {
    throw ArgumentError(_INVALID_MNEMONIC);
  }
  final wordlist =
      DefaultDictionary((Language_Registry[language] ?? const []), language);
  // convert word indices to 11 bit binary strings
  final bits = words.map((word) {
    final index = wordlist.words.indexOf(word);
    if (index == -1) {
      throw ArgumentError(_INVALID_MNEMONIC);
    }
    return index.toRadixString(2).padLeft(11, '0');
  }).join('');
  // split the binary string into ENT/CS
  final dividerIndex = (bits.length / 33).floor() * 32;
  final entropyBits = bits.substring(0, dividerIndex);
  final checksumBits = bits.substring(dividerIndex);

  // calculate the checksum and compare
  final regex = RegExp(r'.{1,8}');
  final entropyBytes = Uint8List.fromList(regex
      .allMatches(entropyBits)
      .map((match) => _binaryToByte(match.group(0)!))
      .toList(growable: false));
  if (entropyBytes.length < 16) {
    throw StateError(_INVALID_ENTROPY);
  }
  if (entropyBytes.length > 32) {
    throw StateError(_INVALID_ENTROPY);
  }
  if (entropyBytes.length % 4 != 0) {
    throw StateError(_INVALID_ENTROPY);
  }
  final newChecksum = _deriveChecksumBits(entropyBytes);
  if (newChecksum != checksumBits) {
    throw StateError(_INVALID_CHECKSUM);
  }
  return entropyBytes.map((byte) {
    return byte.toRadixString(16).padLeft(2, '0');
  }).join('');
}